SPENCER — The monks live in a fieldstone abbey nestled in rolling farmland, supporting their modest lifestyle by selling religious vestments and jam preserves.

But in recent years, the simple monks of Saint Joseph's Abbey have quietly set about building one of the biggest breweries in the state and the first Trappist brewery on American soil. Their sleek 36,000-square-foot brewery — modeled after multimillion-dollar facilities in Europe — has already made its first commercial batches of Belgian-style ale, which will go on sale next week.

It's a big change for the monks, but it was a matter of necessity, said Brother Isaac Keeley, director of the brewery.

''In our little monastic economy, expensesÂ were rising more rapidly than our income,'' he said, standing in his monk's robes in a state-of-the-art beer laboratory inside the brewery. ''We needed to generate more income.''

And generate income it will. The Trappists aim to produce 4,000 barrels of ale this year, the equivalent of 1.3 million 12-ounce bottles, but the brewery has the capacity to generate 40,000 barrels, or more than 13 million bottles of beer.

Only a small number of people have tasted the new ale and toured the plant, situated deep within the monks' 2,000-acre monastic compound in this Central Massachusetts town about a dozen miles west of Worcester. Although the venture has been years in the making, the Trappists have declined to speak publicly about it until this week.

But the secrecy shrouding the enterprise, and the mystique surrounding the monks, should only add to the beers' cachet when it hits store shelves, beer aficionados said.

''Jam will only get you so far,'' said Daniel Kenary, a co-founder of Harpoon Brewery in Boston who consulted with the monks early in the process. ''It'll be interesting to see how it tastes.''

The Spencer monks do not drink much beer. As part of a Roman Catholic religious order started in 1825, they pray seven times a day, live without many modern amenities, such as television, and forgo personal possessions.

They don't hold individual bank accounts, but they still have bills to pay. The abbey, built in the late 1940s on the site of an old dairy farm, is in need of expensive improvements to its roofs, copper plumbing, and distinctive stone exteriors.

At the same time, the monks' numbers are shrinking, meaning fewer contribute to the upkeep and work that support the community. Home to more than 150 monks in the 1950s, the monastery houses 63 today. The average age is 70.

With fewer monks and rising expenses, the Trappists convened a task force of monks and lay people from the community about a decade ago to seek answers to their financial challenges.

They are forbidden by the order from fund-raising, but Trappists in monasteries across the United States sell products from honey to bourbon-infused fudge to pay their expenses. None of the Trappists in the United States has undertaken beer brewing, though in Europe, Trappists have brewed for centuries, making some of the most prized beers in the world.

There are eight Trappist monasteries with breweries in Belgium, Holland, and Austria, according to the International Trappist Association, a Belgian nonprofit that certifies the authenticity of products made by the monks. For a time, one of the beers of Westvleteren Brewery at the Abbey of Saint Sixtus in Belgium was ranked as the top beer in the world on the rating website BeerAdvocate.com.

The Spencer brewery is the most recent to become certified; part of the requirement is that all profits from the venture be used to cover the living expenses of the monks and the maintenance of monastery buildings and grounds.

Brother Damian Carr, the abbot at Saint Joseph's and a monk there for more than 40 years, said he was not initially keen on the idea.

"I thought it was unrealistic'' from a funding perspective, he said, and he feared it might put ''crazy ideas'' into the minds of the brothers who live there. After all, their existence is so spare that they eat their own jam only on Sundays, and consume beer or wine only on significant religious holidays.

But the idea of brewing beer to support the community continued to gain steam, Carr said, particularly after a younger monk who had been ''a beer enthusiast'' in college created bottles of his own homebrew during Christmas season as gifts. Carr said the monks enjoyed the samples and the idea of a brewery gained momentum, eventually forcing him to overcome his reluctance.

"I'm supposed to listen to what the spirit tells us,'' he said.

St. Joseph's sent two monks to Belgium to tour various monastic breweries, hired a professional accountant, and after months of consideration landed on a recipe for a simple ale, based on a type of yeast popular for centuries among European monks.

The new ale contains 6.5 percent alcohol by volume, a higher alcohol content than in the most popular American beers.

''It's the kind of ale monks like to drink,'' said Keeley, noting wryly that people ''love the idea of monks brewing beer.''

Sitting at a stylish wooden desk in a modern white-walled office with a computer, and panoramic window, he pointed to a field and the site of a deep well where the brewery gets its water.

He referred all questions about finances, from the cost of building to the cost of a four-pack, to the beer's distributor, 1098 Distribution Inc. A spokeswoman for the Delaware wholesale distributor would not disclose pricing information.

The monks aren't disclosing details of the financing of the project, either. But the brewery equipment, from a top-of-the-line German manufacturer, can run into the tens of millions of dollars, said Jason Alstrom, co-founder of Beer Advocate magazine. He called the monks' plan to sell 4,000 barrels in their first year ambitious.

"Hoping to sell over 1.3 million bottles of beer or the equivalent is pretty bold for their first year,'' he said.

The monks say limited distribution will begin in Massachusetts by Wednesday. They also plan to supply a small Spencer restaurant situated a quarter-mile from the abbey. It is not yet available in their gift shop.

Carr said the monks opened a keg of the beer on New Year's Day to celebrate the culmination of their efforts and the end of a long process that disrupted their secluded lives with construction crews, marketing teams, and various consultants who have been involved in the project.

''Long term,'' Carr said, ''we'd like to get back to a more normal life.''

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